4. Reinette
Episode: The Girl in the Fireplace (series 2) Reinette is atypical of the other supporting characters on this list as she is based on an actual historical figure. Madame de Pompadour was a highly educated person, an accomplished actress, singer, painter and musician who also happened to be mistress to Louis XV. She is an extremely intelligent woman and the Doctor is mesmerized by both her beauty and her mind. The Girl in the Fireplace is a love story and the Doctors infatuation is utterly believable. This is a real feat as any romantic interest has to compete with the Doctors inherent charisma and self-absorption without becoming a caricature. Reinettes character is written with real warmth and charm which goes a long way toward making her feel like a human being, rather than a textbook account or a plot device. Another reason Reinette stands out is that we see almost her entire existence unfold as the Doctor revisits her several times at various life stages. We watch her grow up and mature in the span of forty minutes and remarkably we truly feel that the Doctor learns to know her deeply and passionately from these brief encounters. The Doctors experiences with Reinette are relatively straight-forward but theres a constant sense of hidden meaning layers of complexity waiting to be unraveled - that gives her character profound depth. Reinette is a person you could spend eternity with and never stop discovering new and exciting facets of her brilliant identity. When the Doctor returns for her and finds her dead we feel his pain just as sharply, stricken by our mutual loss.